Abstract: A method of allocating power among a plurality of signals, at least two of the signals employing different signal formats, located on different channels of the return path of a cable data network, divides a total power available for the signals on the return path in accordance with a minimum value of an average BER for all the signals and allocates power to each of the signals in accordance therewith. Specifically, a number of parameters are obtained including modulation type and symbol rate for each signal format employed on the return path, the AWGN noise floor across the reverse link, the nominal maximum available RF power for transmitting signals on the reverse path. A predetermined BER expression for each of the modulation types employed on the return path is then obtained, each of the expressions requiring a plurality of input values that includes the above-noted parameters.

Abstract: A system for securely transmitting Real Time Protocol voice packets to a remote multimedia terminal adapter over an Internet protocol network. The system features an MTA (a local multimedia terminal adapter) having a key stream generator for generating a first key stream used for encrypting the voice packets. The remote multimedia terminal adapter receives and decrypts the voice packets. Also, the system includes a remote key stream generator for generating the first key stream in order to decrypt the encrypted voice packets and a packet decryptor decrypting the encrypted voice packets using the first key stream, wherein both key stream generators are capable of generating a second key stream to prevent reuse of any portion of the first key stream during the communication session.

Abstract: Methods and apparatus for performing 2:1 downscaling on video data are provided. At least one input matrix of N×N (e.g., N=16) Discrete Cosine Transform (DCT) coefficients is formed from the video data by combining four N/2×N/2 field-mode DCT blocks. Vertical downsampling and de-interlacing are performed to the input matrix to obtain two N/2×N/2 frame-mode DCT blocks. An N×N/2 input matrix is formed from the two frame-mode DCT blocks. Horizontal downsampling is performed to the N×N/2 matrix to obtain one N/2×N/2 frame-mode DCT block.

Abstract: A method (30) and apparatus (10) for scaling selected areas of a graphics display. The method (30) includes removing distortion-sensitive information from the graphics display, scaling or converting the format of the distortion-nonsensitive information, such as from one aspect ratio to another, and then compositing the removed distortion-sensitive information with the scaled distortion-sensitive information. Alternatively, the removed distortion-sensitive is scaled, distortion-free, before combining it with the scaled distortion-nonsensitive information. The apparatus (10) uses a recognition comparator (16) to identify distortion-sensitive information, a graphics remover (18) to remove the distortion-sensitive information, a first scaler (22) to scale the distortion-nonsensitive information, a second scaler to provide distortion-free scaling of the distortion-sensitive information, and a compositer (26) to combine the distortion-sensitive information with the scaled distortion-nonsensitive information.

Abstract: Preamble length of burst communication signals dynamically changed to compensate in changes to linear distortion of a communication channel. Pre-equalization coefficients are provided to network element which pre-equalize communications with the CMTS. Long preamble lengths are used for a select few communications while short preamble lengths are used for the rest of the communication signals. When change in distortion characteristics is detected, a station maintenance is performed on the affected network element and new pre-equalization coefficients are determined and provided to the network element. Alternatively, all communications may be provided with long preamble lengths and communications may continue while the CMTS determines new pre-equalization coefficients.

Abstract: In a cable return path system, a method for performing digital companding adds a predetermined offset to the digital value to be companded, and employs a modified ?-law or a-law companding technique to obtain a reduced bit length digital value. One embodiment of this modified approach adds a predetermined offset (e.g., 129 for a 12-bit implementation) to the digital value before companding and then employs a two-bit chord and a 5-bit step for the 12-bit implementation. The end result is that the performance metrics are not significantly compromised by this bit reduction when compared to current transmission methods without this technique.

Abstract: According to the invention, a circuit that is capable of automated scan testing is disclosed. Included in the circuit are a cryptographic engine, a digital circuit, an input pin, and an output pin. The cryptographic engine capable of performing at least one of encryption and decryption of one or more digital signals. The digital circuit includes combinatorial logic and a number of memory cells. The memory cells have scan inputs connected serially in a scan chain. The input pin and output pin are coupled to the scan chain. At least one of the input pin and the output pin carries at least some cipher text data of the scan chain.

Abstract: Upon determining (201) a need for image recognition facilitation content, a corresponding process (200) first determines (202 and 203) whether adequate local resources are available. When true, those local resources are used (204) to facilitate the desired image recognition. When false, however, one or more remote resources are accessed (205) and supplemental image recognition facilitation content is received (206) and locally used (207) to effect the desired image recognition process. Local memory management can optionally comprise, if desired, deletion (208) of some (or all) locally stored image recognition facilitation content and/or storage (209) of the remotely sourced image recognition facilitation content.

Abstract: A method and system of encoding and decoding digital video content. The digital video content comprises a stream of pictures which can each be intra, predicted, or bi-predicted pictures. Each of the pictures comprises macroblocks that can be further divided into smaller blocks. The method entails encoding and decoding each picture in said stream of pictures in either frame mode or in field mode.

Abstract: A method and apparatus for providing authenticated quality of service reservation in a communication system. According to one embodiment of the invention a signaling controller distributes keys for use by a first quality of service server and a router for establishing quality of service over a communication system.

Abstract: The present invention discloses a system and method for adaptive adjustment of bit budget that favors the allocation of bits to intra coding frames (I frames). Namely, an encoder is able to dynamically adjust the bit budget for each picture type in an image sequence, thereby effecting proper usage of the available transmission bandwidth and improving the picture quality. In one embodiment, the present invention will allocate more encoding bandwidth to a current Intra coding frame when the average quantization level of inter coding frames (e.g., P and B frames) of a previous group of pictures is relatively high.

Abstract: An agile frequency converter provides IF-RF level exchange and notch filtering. System noise and spurious levels generated by channel frequency conversion is reduced in applications requiring broadband combining of frequency converters to form multichannel composite signal. A pair of varactor banks is connected in an arrangement whereby varactor pairs are connected in parallel and capacitor pairs are connected in anti-parallel. Tuning is achieved by circuitry for tuning first and second varactors.

Abstract: A method in a signal processor for filtering samples in a digital signal is provided. An approximate filtered sample is generated as a function of eight samples of the digital signal. A correction is generated as a function of the eight samples, and a filtered sample is generated by modifying the approximate filtered sample with the correction.

Abstract: The present methods and systems provide spectrum management for enhancing upstream performance for cable networks. According to one embodiment, a method of enhancing upstream performance in a cable network includes the steps of measuring performance of an upstream channel at a first data signaling rate; determining whether the upstream channel supports a second data signaling rate based on the performance; and selectively transitioning to the second data signaling rate based on said determination. The second data signaling rate is a higher rate than the first data signaling rate.

Abstract: In a video on demand (VOD) system, methods and apparatus are provided for seamlessly switching back and forth between two pre-encrypted files having changing encryption keys Such switching back and forth may be required when a VOD server stores both a “normal” copy of a movie and a “special” copy such as a “trick-play” version for, e g, fast forward and rewind effects Instead of using keys with changing parities in both streams, the special stream is encrypted with keys using the same parity (even or odd), while the normal stream is encrypted with one dynamic key (odd or even) and one fixed key (even or odd) Other special streams, such as scene branch streams and alternate angle streams can also be accommodated.

Abstract: A double conversion tuner system is disclosed that avoids the problem of degraded performance as a result of radiated interferers. Several selection criteria are described for specifying the parameters of the tuner, including the nominal first or high intermediate frequency, a first local oscillator signal for each desired channel, a nominal second local oscillator signal, and a bandwidth of the first intermediate frequency.

Abstract: A predistortion generator for coupling in-line with a non-linear device produces an output predistortion signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The predistortion circuit comprises a distortion circuit which utilizes the non-linear current flowing through at least one diode, to provide a desired amount of signal attenuation bandwidth. The distortion generator circuitry is always matched to the non-linear device, thereby ensuring a frequency response that is predictable and predefined.

Abstract: A system to transmit a set of programs from a transmitter to a receiver is used to accommodate different levels of security used for each program. When a high level of security is necessary for transmitting or receiving a program the transmitter and/or receiver is operable to accommodate that level of security. Thus, both transmitters and receivers are operable to be reconfigured to encrypt or decrypt, respectively, at different levels. Accordingly, differing amounts of programs can be transmitted or received based on the resource requirements needed at any level of security. Consequently, a high level of encryption/decryption requires more resources and allows the processing of fewer services, while a lower level of encryption/decryption allows more services to be transmitted/received.

Abstract: Method and apparatus to determine the channel to which a TV tuner is tuned from a return loss ratio measurement circuit in a set top decoder. The method comprises generating a plurality of probe signals having frequencies spread throughput the TV channel band, preferably using harmonics of a zero order hold D/A converter. The return loss ratio of the reflected probe signals is then determined and stored as a signature for the TV channel and the signatures can subsequently be used along with new return loss ratio measurements to determine the TV channel to which a TV or VCR tuner is tuned.

Abstract: An improved ingress cancellation filter comprising a Fast Fourier Transform circuit which replaces the analysis filter bank of the prior art to break the incoming signal down into sub bands, an ingress cancellation filter that weights each sub band based upon the probability that the sub band is corrupted by noise, and an inverse Fast Fourier Transform circuit to put the weighted sub bands back together into an output signal and replacing the synthesis filter bank of the prior art. Also, an improved predictor filter which can be used with CDMA circuitry by initializing the predictor filter at the beginning of each spreading interval using the samples received on the first L unused codes of the spreading interval.